1. Field of the Invention
The present invention relates to a method of manufacturing a methanol reforming catalyst, and more particularly relates to a method of manufacturing a highly active and durable catalyst in a technique of manufacturing a reforming gas containing hydrogen as a main ingredient by reacting methanol with steam (or steam and air, depending on cases).
2. Description of the Prior Art
It has been well known that methanol is relatively easily reformed, in the presence of a catalyst, to a gas having hydrogen as a main ingredient. Particularly recently, a steam reforming of methanol has been attracting attention as a hydrogen supplying technique for comparatively small-scale fuel cells. The steam reforming reaction of methanol is expressed by the following formula (A), and its elementary processes in formulae (B) and (C):CH3OH+H2O→CO2+3H2−11.8 kcal/mol  (A) CH3OH→CO+2H2−21.7 kcal/mol  (B) CO+H2O→CO2+H2+9.9 kcal/mol  (C) 
As methanol reforming catalysts, precipitation catalysts of e.g. copper, nickel, chrome, zinc and aluminum oxides have been proposed hitherto as described in Japanese Patent Publication (Unexamined) H3-52643 and Japanese Patent Publication (Unexamined) H5-305234, for example. In these techniques, aluminum nitrate is mainly used as aluminum material and is considered desirable for catalyst production.
In contrast to the steam reforming of natural gas, naphtha and so on, the steam reforming of methanol, which does not require additional equipment for a desulfurizing process or water-gas shift reaction process, is attracting widespread attention as a hydrogen supplying technique for mobile fuel cells such as for use on automobiles, and for stationary fuel cells of comparatively small scale. Since adaptability to load variations and long-term durability are required in these applications, it is essential to improve heat resistance and durability of the catalysts.
Methanol reforming catalysts manufactured by a conventional coprecipitation method are unsatisfactory with respect to heat resistance, and the catalyst activity thereof reduces continuously when used for a long time. This drawback is particularly outstanding under conditions of a reaction temperature of about 300° C. or higher, and the durability of the catalysts at such temperature is extremely low. This problem is particularly outstanding when aluminum nitrate is used as a source of aluminum as described hereinafter on the basis of test results.
Further, in a reaction in which the steam reforming of methanol is combined with partial combustion, the reaction temperature may rise even higher. Thus it is necessary to develop a catalyst durable for a long period of time even when used at a temperature in the order of 300 to 400° C.
Thus, the object of the present invention is to provide a method of manufacturing a highly active, highly heat resistant and durable methanol reforming catalyst which can be used for a long time even under reaction conditions of 300° C. and higher.